No abstract

An efficient synthetic approach to the substituted benzo[b]furan and benzo[b]thiophene scaffolds by iodine‐mediated cyclization of the corresponding enaminones is described. This protocol was applied to a large series of these latter precursors to afford the respective benzoheterocycles substituted at the C‐2 position by a carbonyl group functionality. A study of the factors that control this process reveals that the reactivity depends on the presence of electron‐donor groups in the aryl ring of the aryloxycarbonylic and arylthiocarbonylic moieties.

The synthesis of 2-carbonylindoles was achieved via a iodine-mediated cyclization of the corresponding enaminone precursors, which were formed by reaction of the -arylaminomethylene carbonyl derivatives with N,N′-dimethylformamide dimethyl acetal (DMFDMA). An alternative and more efficient procedure consisted of a similar cyclization of the enaminones, but under solvent-free and grinding reaction conditions. In another iodine-promoted procedure, 2-carbonyl-3-dimethylaminoindoles were synthesized via a one-pot cascade reaction between the -arylaminomethylene carbonyl derivative and DMFDMA.

Efficient Synthetic Approach to Substituted Benzo[b]furans and Benzo[b]thiophenes by Iodine-Promoted Cyclization of Enaminones. -(LABARRIOS, E.; JEREZANO, A.; JIMENEZ, F.; CRUZ, M. D. C.; DELGADO, F.; ZEPEDA, L. G.; TAMARIZ*, J.; J. Heterocycl. Chem. 51 (2014) 4, 954-971, http://dx.

The presented method is used in the synthesis of naturally occurring alkaloid actinopolymorphol B (XVa) which is further transformed into the alkaloid tanakine (XVII). -(ZARATE-ZARATE, D.; AGUILAR, R.; HERNANDEZ-BENITEZ, R. I.; LABARRIOS, E. M.; DELGADO, F.; TAMARIZ*, J.; Tetrahedron 71 (2015) 38, 6961-6978, http://dx.